Since it's just one among many, a comment should work: Tell them (preferably adding a link) that Stack Overflow uses English. It shouldn't be a serious issue though; much less than 1% of answers are in Spanish.

Personally, I feel we should gently remind people of it, since it is simply really hard for some folks.

It's an English language site, though. How can the majority of users evaluate whether the post is spam or offensive if it's in a different language? I know I wish I were multilingual, but I'm not.
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jonscaOct 22 '11 at 19:52

It's Portuguese actually, but why would it be offensive? Meaning, why assume bad about people(and this is a technical, non-political site also) ? I just feel we should be gentle to them, rather than abruptly closing...
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AdelOct 22 '11 at 19:57

4

There's nothing ungentle about closing a question or deleting an answer. People read more into those actions than they should. Most if not all moderators would leave a comment on the deleted answer that still can be read by the user who posted it.
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jonscaOct 22 '11 at 20:01

1

I'm not saying it's offensive in any way, but aside from using simple heuristics, there's no way for me to tell, in any language I don't know, not just in this case.
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jonscaOct 22 '11 at 20:07